1. Field of the Invention
This invention relates to a device for guiding or pulling magnetic implants in the body, and more specifically such devices and methods that provide and/or utilize an articulated, guided magnet assembly.
2. Discussion of the Prior Art
Magnetic stereotaxis systems are known in the art. One such system is disclosed in McNeil et. al., xe2x80x9cFunctional Design Features and Initial Performance Characteristics of a Magnetic-Implant Guidance System for Stereotactic Neurosurgery,xe2x80x9d IEEE Trans. on Biomed. Engrg. 42 793 (1995). The system described in this publication is a specialized application of multi-coil magnetic actuators. Other systems for magnetic surgery include those in which manually manipulated solenoids are moved about the body, such as the magnetic stereotaxis system described in Gilles et al., xe2x80x9cMagnetic Manipulation Instrumentation for Medical Physic Research,xe2x80x9d Rev. Sci. Instrum. 65 533 (1994). The aforementioned two articles are hereby incorporated by reference in their entirety.
The systems described in the prior art have the disadvantage in that hand-held magnets are not coordinated with imaging in a precise way and cannot apply field or force gradients accurately in needed directions. Also, it has been difficult or impossible, from a practical standpoint, to apply strong magnetic fields to provide guidance or force deep within a body. Furthermore, the magnetic stereotaxis system and other similar systems with multi-coil arrangements require the solution of magnetic field equations with those solutions are not being easy to find or once found are ill-behaved. Therefore, it would be an advance in the art to provide a magnetic surgical system in which equations having simpler and more well behaved field solutions could be expected, and that is also capable of providing a strong magnetic field deep in a patient""s body in a manner coordinated with an imaging device.
It is therefore an object of the invention to provide a surgical system that provides precise imaging in combination with accurate application of magnetic fields and/or force gradients in required directions for moving or guiding a magnetic implant.
It is a further object of the invention to provide a surgical system that provides precise imaging in combination with an accurately applied magnetic field, including magnetic fields stronger than are possible with hand-held magnets.
It is yet another object of the invention to provide a surgical system and method for providing precise imaging in combination with a magnetic field that can provide guidance or force deeper within the body than is practical with hand-held magnets, and in some instances far deeper.
It is still another object of the invention to provide an improved magnetic guidance system that can provide a combined guiding field and force-applying field gradient in the same desired direction through use of an articulated magnet, such fields to be used for guiding, and possibly motivating, a magnetic structure or device such as a magnetic seed or magnet of a catheter.
It is yet another object of the invention to provide an improved magnetic guidance, and possibly motive force, system that can be controlled with increased simplicity relative to prior art magnetic guidance systems.
It is yet an additional object of the invention to provide a robotically controlled magnetic system to locate an electromagnetic coil in a manner in which simpler and possibly more effective, including simpler and more well behaved, field solutions can be achieved in guiding magnetic surgical devices such as magnetic seeds and the magnetic tips of catheters.
It is still another object of the invention to provide a robotically controlled magnet system to locate a permanent magnet or magnets in a manner in which more effective field solutions can be achieved in guiding and motivating magnetic surgical implants.
These and other objects are achieved by the various embodiments of the invention as exemplified in the specification and claims hereof which includes, in a first embodiment, a moveable magnet assembly configured to provide a magnetic field in a patient when the magnet assembly is operated; and an imaging system configured to provide an image of a magnetic implant in the patient. Preferably, a bed or other support is provided for the patient. The magnet assembly is preferably robotically controlled, and may comprise either a permanent magnet or an electromagnet that is brought into the proximity of the patient. The electromagnet may be either a normally conducting electromagnet (i.e., one having resistive conductor coils) or a superconducting electromagnet. The moveable magnet assembly may comprise a track and gimbal support having radial and/or rotational motion components, as well as translational components. The imaging system may comprise two medical image display screens such as x-ray display screens, a first of which is mounted below the bed and a second of which is mounted horizontally and above the bed at a side of the bed, and further comprising two imaging tubes such as x-ray cameras, a first of which is mounted above the bed opposite the first x-ray display screen, and a second of which is mounted above the bed on a side of the bed opposite the second x-ray display screen. Alternately (or in addition thereto), a portion of the imaging system may reside on and be configured to move with the moveable magnet assembly.
In accordance with another significant aspect of the invention that is noteworthy both individually and in conjunction with the other aspects of the invention, it has been discovered that significant magnetic fields in all directions and at all locations in an operating region, into which a patient""s body part desired to be operated on may be placed, such as a brain, may be achieved by pure rotation. This advantage is achieved by a magnet design in which a ratio of side magnetic field to axial magnetic field magnitude is large, as explained in more detail below.
While a brief explanation of the invention has been given, a fuller understanding of the invention may be attained by referring to the drawings and description of the preferred embodiments which follow.